Density functional theory calculations of the oxidative dehydrogenation of propane on the (010) surface of V2O5
Density functional theory calculations of the oxidative dehydrogenation of propane on the (010) surface of V2O5
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DOI：
10.1021/jp001746m
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发表时间：
2000-12-28
影响因子：
3.3
通讯作者：
Boulet, P
中科院分区：
文献类型：
--
作者：
Gilardoni, F;Bell, AT;Boulet, P
采用密度泛函理论和氧亲核性计算方法，研究了丙烷在V_2O_5（010）面上的氧化脱氢反应。这些计算表明，在能量上优选的初始步骤是丙烷的解离吸附，以形成异丙氧基和羟基物种。需要通过V-O-V桥键合的两个V=O基团[O（1）]。其中一个氧钒基攻击丙烷的β-C原子并转化为V-OCH 2（CH 3）（2）物种，而醚氧钒基转化为V-OH基团。该过程的活化势垒为9.4 kcal/mol。也可以发生解离吸附以形成正丙醇盐，但该过程的活化势垒为14.5 kcal/mol。丙烯和水通过一个协同过程形成，其中异丙氧基的一个甲基的H原子与O（3）H基团反应。探索这一步骤的替代途径表明，O（1，2，3），O（1）H和O（2）H都没有足够的反应性。这些发现是在良好的定性协议与实验观察丙烷ODH的机制和动力学。
Density functional theory and the calculations of oxygen nucleophilicity have been applied to an analysis of the oxidative dehydrogenation (ODH) of propane on the (010) surface of V2O5. These calculations show that the energetically preferred initial step is the dissociative adsorption of propane to form i-propoxide and hydroxyl species. Two V=O groups [O(1)] bonded by a V-O-V bridge are required. One of the vanadyl groups attacks the beta -C atom of propane and is converted to a V-OCH2(CH3)(2) species, whereas the ether vanadyl group is converted into a V-OH group. The activation barrier for this process is 9.4 kcal/mol. Dissociative adsorption to form an n-propoxide can also occur, but the activation barrier for this process is 14.5 kcal/mol. Propene and water are formed via a concerted process in which an H atom of one of the methyl groups of i-propoxide reacts with an O(3)H group. Exploration of alternative pathways for this step reveals that neither O(1, 2, 3), O(1)H, nor O(2)H are sufficiently reactive. These findings are in good qualitative agreement with experimental observations concerning the mechanism and kinetics of propane ODH.